Really confused on how to use my geth wallet

There doesn't seem to be any actual "geth" wallet that I created using a guide on how to start mining. BUT, it's this wallet address that I use as my miner ID on ethermine. I want to be able to transfer my ether balance to something like coinbase or poloniex for trading, but I really can't seem to make it happen. I have ether sitting there.. but I can't do anything with it!Help!